As the heyday of the lumber camps faded, a young scholar named Franz Rickaby set out to find songs from shanty boys, river drivers, and sawmill hands in the Upper Midwest. Traveling mostly on foot with a fiddle slung over his shoulder, Rickaby fell into easy conversation with the men, collecting not just the words of songs, but the tunes, making careful notes about his informants and their performances. Shortly before his groundbreaking and much-praised...